In a capacitor-start motor, what is the role of the start capacitor?

In a capacitor-start motor, what is the role of the start capacitor?

• A. To increase efficiency
• B. To initiate rotation
• C. To maintain speed
• D. To reduce power consumption

Answer: (B)

In a capacitor-start motor, the start capacitor plays a crucial role in initiating the rotation of the motor's rotor. When the motor is powered on, the start capacitor is temporarily connected in series with the start winding. This arrangement creates a phase shift in the current, which results in the creation of a rotating magnetic field that produces the necessary torque to overcome inertia and start the rotor spinning. Once the motor reaches a certain speed, typically around 70-80% of its full speed, a switch (often a centrifugal switch) disconnects the start capacitor and start winding from the circuit. At this point, the motor runs efficiently using only the main winding. Therefore, the start capacitor is essential during the initial phase of operation to get the motor up to speed. It's important to understand the different functions of capacitors in electrical motors; for instance, while other types of capacitors can address efficiency or power factor issues, the specific role of the start capacitor is to provide the additional torque needed at startup. This distinguishes its function from concepts like efficiency maintenance or power consumption reduction, which apply in other contexts or motor types.

In a capacitor-start motor, the start capacitor plays a crucial role in initiating the rotation of the motor's rotor. When the motor is powered on, the start capacitor is temporarily connected in series with the start winding. This arrangement creates a phase shift in the current, which results in the creation of a rotating magnetic field that produces the necessary torque to overcome inertia and start the rotor spinning.

Once the motor reaches a certain speed, typically around 70-80% of its full speed, a switch (often a centrifugal switch) disconnects the start capacitor and start winding from the circuit. At this point, the motor runs efficiently using only the main winding. Therefore, the start capacitor is essential during the initial phase of operation to get the motor up to speed.

It's important to understand the different functions of capacitors in electrical motors; for instance, while other types of capacitors can address efficiency or power factor issues, the specific role of the start capacitor is to provide the additional torque needed at startup. This distinguishes its function from concepts like efficiency maintenance or power consumption reduction, which apply in other contexts or motor types.